1. Field of Invention
This invention relates to a grommet. In particular, this invention relates to a grommet that prevents a wire harness from scraping against an opening of an automobile body panel, when a corrugated tube holding the wire harness is being inserted into the opening. This invention further relates to a grommet that prevents intrusion of water, moisture and sound through the opening of the automobile body panel into the inside of the automobile panel.
2. Description of Related Art
Conventionally, a grommet is used to prevent a wire harness from scraping against an opening in an automobile body panel when a corrugated tube holding the wire harness is being inserted into the opening. The grommet is also used to prevent intrusion of water, moisture and sound into the inside of the automobile body panel through a gap between the opening in the automobile body panel and the corrugated tube.
FIGS. 7(a) and 7(b) are drawings to explain an example of a conventional grommet into which a corrugated tube is inserted. In FIGS. 7(a) and 7(b), a circular trough 1a and a circular ridge 1b are alternatingly provided around the outer peripheral surface of the corrugated tube 1. A wire harness 2 is inserted into the inner periphery of the corrugated tube.
In FIG. 7(b), a grommet 3 is provided with a large-diameter tapered portion 5 and a small-diameter cylindrical portion 6 that extends from the tapered side of the large-diameter tapered portion 5 and is sized so that the corrugated tube 1 can be inserted. The tapered portion 5 has a circular recess 5a around an outer peripheral surface at the enlarged side of the tapered portion 5 for engaging with a mounting hole 4a provided in an automobile body panel medium 4.
Generally, the small-diameter cylindrical portion 6 is positioned outside of a passenger compartment. The corrugated tube 1 is fixed to the grommet 3 by wrapping a tape 7 around a connection between the corrugated tube 1 and the small-diameter cylindrical portion 6. Thus, since the grommet 3 is mounted between the corrugated tube 1 and the panel 4, the grommet 3 can hold the corrugated tube 1 such that intrusion of water, moisture or sound is prevented. In addition, a wire harness 2 can be wired inside and outside of the passenger compartment through the mounting hole 4a in the panel 4.
However, with the conventional grommet 3, the corrugated tube 1 is inserted into the small-diameter cylindrical portion 6 and fixed to the grommet only by wrapping a tape around the connection between the corrugated tube 1 and the small-diameter cylindrical portion 6. Therefore, the corrugated tube 1 easily slides in an axial direction of the corrugated tube 1. In addition, the wire harness 2 might also slide in an axial direction of the corrugated tube due to the sliding of the corrugated tube. Thus, a layout of the wire harness may become out of position.
To resolve this problem, the number of turns of the tape 7 wrapping around the connection between the small-diameter cylindrical portion 6 and the corrugated tube 1 is increased. However, this method requires a difficult mounting task and takes a long time. Accordingly, the efficiency of the mounting of the corrugated tube 1 is reduced.
FIGS. 8(a) and 8(b) show a grommet developed by the inventors of the present invention to resolve the problem described above. In FIGS. 8(a) and 8(b), a grommet 11 is provided with a grommet body that has a recess 13a around the outer peripheral surface to engage with an opening 12a formed in an automobile body panel 12.
In addition, the grommet body 13 has an insertion aperture 13b to insert the corrugated tube 1 therein. A circular ridge 14a and a circular trough 14b are provided alternatingly around the inner peripheral surface of the grommet body 13 surrounding the insertion aperture 13b. The circular ridge 14a and the circular trough 14b engage with circular trough 1a and circular ridge 1b of the corrugated tube 1, respectively.
Due to the structure of the grommet 11, when the corrugated tube 1 is being inserted into the insertion aperture 13b, a diameter-expanding machine (not shown) is inserted into the insertion aperture 13b to expand the insertion aperture 13b in a radial direction. Then, the corrugated tube 1 is inserted into the insertion aperture 13b. The circular ridge 14a and the circular trough 14b respectively engage with the circular trough 1a and the circular ridge 1b of the corrugated tube 1. Thus, the corrugated tube 1 is prevented from sliding in an axial direction of the corrugated tube against the grommet 11.
Thus, the grommet 11 must be used with a diameter-expanding machine, which is inserted into the insertion aperture 13b to expand the insertion aperture 13b in a radial direction, when the corrugate tube 1 is inserted to the insertion aperture 13b. Accordingly, the diameter-expanding machine is always required. In addition, the number of operative steps required for the insertion task increases. Therefore, further improvement is required.
Accordingly, the object of the present invention is to make it easier to mount a corrugated tube into an insertion aperture of a grommet through a slit, and thus, to improve the efficiency of the mounting task for the corrugated tube, while waterproofness and soundproofness of the grommet are not adversely affected, by tightly closing the slit after mounting the corrugated tube.
To achieve the above and/or other goals, the present invention provides a grommet into which a corrugated tube having a circular ridge and a circular trough alternatingly on an outer peripheral surface of the corrugated tube is mounted. The grommet includes a body having a recess around at least part of an outer peripheral surface thereof and an insertion aperture into which the corrugated tube is insertable. The recess is engageable with an opening provided in a panel. The body also has at least one trough and at least one ridge provided on an inner peripheral surface surrounding the insertion aperture. The trough and the ridge of the body are respectively engageable with the circular ridge and the circular trough of the corrugated tube. The body further includes a slit extending from the insertion aperture to the outer peripheral surface of the body so that the slit can be opened and closed. Facing surfaces of the body on opposite sides of the slit are inclined at a predetermined angle with respect to a line within a plane coextensive with the central axis of the of the insertion aperture. The outer peripheral surface of the body is also inclined at the same predetermined angle with respect to the line.
In another aspect of the present invention, there is provided a grommet to receive a tube. The grommet that includes a grommet body having a generally planar portion, a curved portion and tapered portions in an outer peripheral surface, and an insertion aperture to insert a corrugated tube. Each of the tapered portions extends between an end of the plane portion and an end of the curved portion. The tube may be a smooth-wall tube or a corrugated tube having a circular trough and a circular ridge alternatingly on an outer surface of the corrugated tube. The grommet body also has a slit extending from the insertion aperture to the plane portion. Facing surfaces of the grommet body on opposite sides of the slit are inclined at predetermined angle with respect to a line perpendicular to the central axis of the insertion aperture. The tapered portions are also inclined at the predetermined angle with respect to the line.
In the above described cases, since a slit is provided that extends from the insertion aperture to the outer peripheral surface of the grommet body, and the facing surfaces of the grommet body on opposite sides of the slit can be separated, the tube is easily mounted into the insertion aperture through the slit. In addition, after mounting of the tube, the facing surfaces are contacted, i.e., the slit is closed; thus, the tube is prevented from slipping out from the insertion aperture.
Since the surfaces on opposite sides of the slit faces and are inclined at a predetermined angle with respect to a line perpendicular to the axis of the insertion aperture, and the outer peripheral surface of the grommet body is inclined at the same predetermined angle with respect to the line, the facing surfaces of the grommet body on opposite sides of the slit can tightly contact one another when the grommet body engages with a groove in a panel medium. Accordingly, water, moisture and sound are prevented from entering into the insertion aperture through the slit; thus, waterproofness and soundproofness are not adversely affected.
In addition, since the facing surfaces are inclined at the predetermined angle with respect to the line perpendicular to the axial direction of the insertion aperture, the width of the gap of the slit can be wider. Accordingly, when the grommet body is molded using a die, the die cutting for the slit can be performed easily. Thus, the molding operation of the grommet body becomes easier.
In another aspect of the present invention, to resolve the problem described above, there is provided a grommet that has a tongue on at least one surface of the grommet body where an end of the insertion aperture is located. The tongue extends from an edge of the insertion aperture. The corrugate tube can be fixed to the tongue by wrapping a tape therearound.
In this case, since the corrugated tube can be fixed to the tongue by wrapping a tape therearound, the corrugated tube is fixed to the grommet more firmly.
In accordance with a further aspect of the present invention, to resolve the problem described above, there is provided a grommet that includes a tongue having a ridge and a trough alternatingly there along. The ridge and the trough respectively engage with the circular trough and the circular ridge of the corrugated tube.
In this case, in addition to fixing the corrugated tube by wrapping a tape, the ridge and the trough provided on a surface of the tongue can engage with the circular trough and the circular ridge, respectively. Thus, the corrugated tube is prevented from sliding in an axial direction of the insertion aperture of the grommet body.
In another aspect of the present invention, there is provided a method for mounting a corrugated tube having an alternating ridge and trough in an outer peripheral surface of the corrugated tube into an insertion aperture of a grommet. The method includes opening a slit provided in the grommet. The slit extends from the insertion aperture to an outer peripheral surface of the grommet. The corrugated tube is then inserted into the insertion aperture through the slit. The position of the corrugated tube is adjusted so that the corrugated tube is located on a tongue. The tongue is provided on a surface of the grommet, and the surface includes an end of the insertion aperture. Next, a tape is wrapped around the corrugated tube and the tongue. Lastly, the slit is closed by engaging a recess provided in the outer peripheral surface of the grommet with a panel opening.
According to the method described above, a diameter-expanding machine is not required and the mounting operation of the corrugated tube to the grommet is simplified by using the slit.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawings.